In recent years, various network services are provided over IP networks typified by the Internet, but a dedicated edge system is required for each network service. Note that the term “network service” used in the following description means a service that is provided at an edge to an IP network by a telecommunication carrier through ISP access, BRAS (Broadband Remote Access Server), BAS (Broadband Access Server), BNG (Broadband Network Gateway), SBC (Session Boarder Controller), SSE (Subscriber Service Edge), VoIP (Voice over IP) gateway, CDN (Content Delivery Network), IMS (IP Multimedia Subsystem), or the like.
For example, as shown in FIG. 1, a mobile system 1 including IMS for implementing VoIP and the like in addition to BSC (Base Station Controller), RNC (Radio Network Controller), and the like is provided as an edge system for a mobile communication network. SSE 2 including, for example, BAS and SBC is provided as an edge system for a fixed network.
FIG. 2 shows an example of an edge system that uses a BRAS as a LAC (L2TP Access Concentrator) (see FIG. 1 of NPL 1). An access network 3 and an ISP network 7 are connected through a BRAS 4, an IP network 5, and a LNS (L2TP Network Server) 6. A user terminal makes a request to the BRAS for session establishment, and upon successful authentication, the BRAS connects to the LNS (L2TP Network Server) based on L2TP (Layer 2 Tunneling Protocol), thereby enabling the ISP network 7 to provide a service to the user.
Moreover, PTL 1 has proposed a network access system that makes it possible to extend and modify services by, instead of using an inflexible and proprietary edge router, distributing the functionality of the edge router.